1. Field of the Invention
The present invention is related to a testing method for a polarizing plate. The method includes processes of a selected beam of light passing through a filter, a polarizer, a concave lens or a filter, a mirror, a concave lens and finally to an optical film; the optical film is rotated along z-axis to ascertain that if there is any variation of shade in an optical domain, in order to differentiate defective samples from qualified ones.
2. Description of the Prior Art
In a process of polarizing coatings, a pre-checking is necessary to prevent defects in products while feeding a new material of optical coatings. However, there are some defects, such as gooseflesh in the coating, undetectable by naked eyes. The gooseflesh results from non-uniform thickness of the polarizing coating and are not detected apparently by the naked eyes until the polarizing coating is preprocessing to half-finished, so that increase the production costs.
When an optical coating is preprocessing to half-finished, a check by crossing polarized beams transmitting is necessary to ascertain order of severity of film thickness. It is late to use the checking method because it helps little for costs to differentiate defective samples from qualified ones until the coating is half-finished.
It is also difficult to reflect defects to a factory owner who offers the material of optical coatings. Non-uniformity of the film thickness cannot be reflected to the factory owner immediately because the non-uniformity cannot be detected by naked eyes until the coating is half-finished. Moreover, there is no precise standard for the non-uniformity, which is difficult to describe; as a result, the factory owner has no idea of the defects and improving method.
A motive of the present invention is based on the foregoing; however, to ascertain the non-uniformity and reflect immediately, it should not take too much time to check the defects. The most important is to appear the shortage of non-uniform thickness and the non-uniformity can be detected by the naked eyes and no instrument for checking is needed.